Friction clutch and release lever mounting



y 7, 1957 w. v. THELANDER 2,791,307

FRICTION CLUTCH AND RELEASE LEVER MOUNTING Filed March 8, 1952 III/III 3 lm wzr W Vincent TheZander United States Patent FRICT-ION CLUTCHAND RELEASE "LEVER MOUNTING -W. Vincent .Thelander, Toledo, Ohio, ,assignor to Dana Corporation, Toledo, Ohio, a corporation of Virginia Application March =8, .1952, SerialNor 275,633

14 .Claims. (Cl. 19299) This invention :relates to frictionclutches for useron automobiles, tractors, and othervehicles, and suitable also for industrial applications.

In clutches like that disclosed in my Patent 2,214,780, issue'dSeptember 1 7, 1940, the pressure-plateismoved toward engaged :position by novel spring-pressed release levers and is :moved toward disengaged position by spring means acting between the backplate .and'drive lugson the pressureplate. "However, these lugsprojecting through openings in the back plate with a predetermined operating clearance caused an objectionable rattle unless special-provisions were made to eliminate the hammer noise. An

example ofsuch-special provisions is disclosed in-Patent 2,515,277, issuedto'E. M. DeCoursey and-me-on 'July'1-8,

-In.my.-copending applications, *Serial'No. 656,327, filed "March 22, 21946, now PatentNo. 2;589;308andSeria1'No.

244,174, filed August 29, 1951, now Patent No. 2,738,850, I. disclosed constructions constituting other solutions to the problem. :ln those constructionsleaf springs are provided betweentheradiallyinner-portion of the backplate and .theL-backof the pressure plate-to transmit drivefromzthe back plate to the pressure plate and keep the latter centered relative to the baclt plate, these leaf springsserving also :to keepthezpressure plateiin assembled relationto the-back:plate in the shipment o-f-the. clutch from'theplant of thetclutchimanufacturer tothe plant of the automobile .manufacturer, soithat it is ready for installation upon :arrival.

.catedzandexpensive and itis therefore theprincipal object Those designs, however, are stillfairly compliof my inventionctoprovide another'design that is simpler and less expensive, this design eliminating the leaf springs which representeda sizable fraction of the cost.

in" the present. design the pressure -plate 'has drive lugs slidable.in -holesinithe back plate, and theselugshavethe usual adjusting screws thereon for engagement with the :release; levers carriedon-the backplate, and return-links .arezprovided, one inconnection with each of the release .leversdetachably :pivotally. connecting the outer ends :thereof-to;the headssof theadjusting screws in suchaway thatrthe screws can" be'adjt1sted whenever necessary, with- .out disconnecting the release levers therefrom, "the return linksalso serving as friction. drag'means to frictionallyreisist lateral movement of the screw heads relativeto the levers :so as to-keepthe lugs on the pressure plate'from .hamemring on thesides of the holes in the back plate. Each return link,-in order to add resilience to the-friction andbent upon themselves to define shoulders which, when the arms are extended through holes in the release lever and through notches in the ends of a spring steel retainer plate mounted on the adjustingscrew under the head :a lever support. In accordance with the two patents men- "tioned, a plurality of release levers 14 are provided which 2,791,307 Patented May 7, 1957 thereof, are adapted to snap intoplace behind'jthe retainer plate to tie the release lever detachablyand pivotally to the "headzof the adjusting screw and yet securely enough so that there 'is'nodangerof the return link-becoming disconnectedin 'the operation of the clutch -at :the highest speeds, not.even'whena wrench visapplied to-thefhead of the adjusting screw'to turn it in a takeupfl'djustment.

V Theinventionzisillustrated in'theaccompanying draw- -ing, in.which-- vFig. .1 is a rear viewof a clutch embodying-my invention, only one of three release leversthat are provided being shown, and the return link connecting the release ilever with the head of the'adjusting screwonthe pressure :plate;

Fig. 2 is a section on the linei2-2of Fig. 1;

Fig. "3 is atsection 'onthe line 3-:-3of Fig..1'on"a larger -scale;-and

Figu4 is aview of the retainer plate removed and shown -onthe=same-scaleas it appears in Figs. 1 and'2.

The same; reference numerals are applied to corresponding parts in these four views.

iReferring'to Figs. 1 and 2, the'reference numeral 5 is -applied to a.flywheel mounted on-therear end of the usual .sengine crank shaft and forming the driving element. :6

designates :a clutchdisk having .the usual facings"7 for engagement with the flat back face 8 on the fiywheel and the flat front face 9 on the pressureplate 10, the disk 6 being mounted in'the usual way bymeans of a:hub portion splinedwon the front end of ashaft constituting the driven ,elernentian'd extending rearwardly'from the clutch into 'the gear box of the transmission inthe usual'way. The :clutch illustrated is like that disclosed in my Patent No. 2,214,780ymentioned above, but it should'be understood ":thflt thepresent invention is not limitedto thatparticular 'clutch but may be used on any friction clutch where a -sirn'ilar problem of providing anti-rattle means ispresented;

that is to say, in any friction clutch wherein the pressure -.-plate"has rearward projections or drive lugs like that indi- .:cated. at 1 1, projecting through-openings like that indicated :at :12, in a back plate like that indicated at'13, or inback :plate segments, bearing inmind that in an=ea1'-lier"1 hedander et al. 1,985,301, issued December 25, 1934, the

conventional back plate was eliminated in one form, and

a znumbersof separate brackets fastened to the flywheel werezsubstituted, each bracket-forming what was called rmultiplied'through the levers 14 for clutch engagement,

it is'apparentthat there is an appreciable'mechanical advantage in'the disengagement of the clutch by reason of the fact that the springs 15 are closer to the pivots17 than the inner ends 16 of the levers where the throw-out hearing engages, thus making for lighter pedal action. This arrangement is also of advantage from the standpointthat there is very little loss of spring pressure when the clutch facingsi become worn, because so little expansion of the springs is permitted for a given amount of wear of the *facings. The lugs 11 have screws 19 threaded in 1ongitudinal holes 20 provided therein, and, when'the heads 21 of the screws 19 are properly adjusted relative to the outer ends 18 of the levers 14, lock nuts 22 on the shanks of the screws 19 are tightened to lock the screws in adjusted position. 'In taking up for wear on the facings 7, the screws 19 .are backed up a turn .or so after the lock nuts 22 have been loosened, and when the correct relationship of the clutch parts has been restored in that way, the screws 19 are locked again in adjusted position by tightening the nuts 22. Washers 23 are held in place on the adjusting screw 19 on lugs 11 by lock nuts 22, and these washers are adapted to serve by abutment with the back plate 13 to limit the movement of the pressure plate away from the back plate when the clutch assembly is being shipped from the plant of the clutch manufacturer to the plant of the automobile manufacturer, so as to keep the springs 15 caged under the release levers 14 and make the clutch ready for installation upon arrival at its destination. These washers 23 play no part in the operation of the clutch otherwise.

The lugs 11, which are cast integral with the plate 10, are substantially square in cross-section and milled ofi' fiat and parallel on the opposite sides 24, the holes 12 through which .the lugs 11 project being rectangular in form and having the opposite sides 25 thereof finished flat and in parallelism to one another and so spaced in relation to the width of the lugs 11 between the sides 24 to receive the lugs with an easy working fit, whereby drive is transmitted from the back plate to the pressure plate without the use of any intermediate leaf springs, such as are disclosed in the two aforementioned copending applications.

The release levers 14, in addition to applying the engaging pressure, in accordance with my present invention are equipped to serve the further functions of retracting the pressure plate in the disengagement of the clutch and reducing if not entirely eliminating hammer noise, thereby greatly improving the operation of the clutch generally. The return links and cooperating retainer plates 31 for the performance of these functions add very little to the cost of manufacture of the clutch. The plates 31 are rectangular pieces of tempered spring steel. each having a center hole 32 to receive the shank of the associated screw 19, and notches 33 in the middle of each end to receive the end portions 34 of the arms 35 of the associated U-shapcd return link 30 when the latter is detachably connected or coupled thereto, as shown in Fig. 3. The plate 31 is assembled on the shank of the screw 19 before the lock nut 22 is put. on and hence cannot fall off even when the link 30 is not attached to it. Its springiness facilitates connection with the end portions 34 which are bent into outwardly diverging relation, as clearly appears in Fig. 3, and have their extremities bent inwardly upon themselves as indicated at 36 to define shoulders 37 that are adapted to snap into place behind the notched end portions of plate 31 to tie the inner end portion 18 of the associated release lever 14 detachably and pivotally to the head 21 of the screw 19 and yet securely enough so that there is no danger of these parts becoming disconnected in the operation of the clutch at the highest speeds, not even when a wrench is used on the head 21 of the screw 19 to turn it in a clutch takeup adjustment, the arms 35 of the link 30 being spaced far enough apart to afford ample working space on both sides of the screw head 21. The link 30 is made of spring wire stock so that the arms 35 which extend freely through holes 38 provided in the bottom of the transverse channel shaped fulcrum rib 39 that is formed on the inner end 18 of the lever 14, are adapted to be spread apart enough to let the shoulders 37 pass through notches 33, after which they snap into place behind the plate 31 to complete the connection. The angle of inclination of the shoulders 37 relative to the plane of the plate 31 is enough to insure a tight fit as these shoulders wedge inwardly into place under the plate. The springiness of plate 31 is beneficial in that respect because the notched ends of the plate will flex inwardly toward the lever 14- enough to let the shoulders 37 move home. Also, the cross-portion 40 of the U-shaped return link 30 is bowed inwardly to engage the back of lever 14 only at the mid point 41 of the crossportion and thus permit the ends of the cross-portion to be flexed toward the lever 14 enough to let the shoulders 37 move home behind plate 31, whereby to provide a further spring pressure holding the fulcrum rib 39 of the lever in line contact pivotal engagement with the head 21 of the adjusting screw diametrically of the latter. Plate 31 is shown as straight in Fig. 3 but it will be understood that in actual practice it is flexed to some extent at both ends toward the lever 14 to equalize the spring pressure due to straightening deflection of the bowed cross-portion 40 of link 39.

In operation, the lugs 11, of which there are three in circumferentially spaced relation, on the same radial center lines ab, ac, and ad with three release levers 14, support the pressure plate 10 in centered relation to the back plate 13 and also transmit drive from the back plate to the pressure plate, the lugs 11 being slidablc freely in holes 12 provided in the back plate so as to move to engaged position under action of springs 15 and to disengaged position under action of release levers 14v Positive return of the pressure plate upon disengagement of the clutch is obtained by the return links 30 cooperating with the retainer plates 31, the links 30 being designed, as pointed out above, to be snapped into place in the assembling of the clutch and yet be attached securely enough so that there is no danger of accidental disconnection at high engine speeds, nor even when a wrench is applied to the head 21 of the screw 19 for adjustment of the clutch, as to compensate for wear of the facings 7 on the clutch plate 6. The return links 39 also constitute resilient friction drag means arranged to frictionally resist lateral movement of the screw heads 21 relative to the cooperating ends of levers 14 enough to prevent hammer noise. The construction is also advantageous in the shipment of the clutch assembly because the washers 23 serve by engagement with the back plate 13 as stops to limit outward movement of the pressure plate 10 away from the back plate. The clutch is well ventilated, due to the fact that the pressure plate 19 is exposed throughout the major portion of its circumference between the radially extending channel-shaped spoke portions 42 that provide the flanges 43 for support of the pivot pins 17 on which the release levers 14 are mounted, these spoke portions being attached to the flywheel by screws entered in holes 44 provided in the peripheral attaching flange portion 45 that interconnects the outer ends of the spoke portions.

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn to cover all legitimate modifications and adaptations.

I claim:

1. In a clutch comprising, in combination, a flywheel, a back plate carried thereby, a driven member, an axially movable pressure plate having a plurality of rearwardly extending drive projections in circumferentially spaced relation received in registering openings provided therefor in said back plate with a fit close enough to transmit drive but with sufiicient clearance to permit relative sliding movement, spring means to transmit engaging pressure to said pressure plate, and release levers pivoted relative to the back plate for causing disengagement of the clutch, the same having end portions disposed adjacent the outer ends of the drive projections, the improvement which consists in the provision of means pivotally connecting the drive projections with the adjacent ends of the release levers so that the pressure plate is positively retracted by the levers upon depression of the other ends of said levers, the pivotal connecting means including friction drag means arranged to exert appreciable frictional resistance to lateral movement of the projections relative to the levers in the normal operative position of the levers, whereby to prevent hammering of the projections on the sides of the openings, said friction drag means constituting the sole anti-hammer means in said clutch.

2. In a clutch comprising, in combination, a flywheel, a back plate carried thereby, a driven member, an axially tnovable pressure plate having .a plurality r of rearwardly .extendingdrive projections in circumferentially spaeed relationsreceived in registering openings;provided-therefor, in said back=plate, spring means to'transmitengaging pressure to .said pressure;- plate, and release levers; pivoted .relative tothe-back plate'for causing disengagement of the clutch,'thesame having-end portions disposed adjacent the outer ends of the drive projections, the improve- ;ment-which consistsin the provision ofmeans flexibly connecting the drive projections with the adjacent ends of the release levers}comprisingvgenerally U-shaped return link members, one associated with each leverand related driveprojection, having the .cross;portion of :the U straddlinga portion ofthe end of the lever permitting pivotal-movement ofthe latterand having the arms of the U extendingtoward the projection and attached to the opposite ends ofvan elongated plate thatis rigidly supported intermediate its ends on (the drive projection in transverse relation thereto, soithat theleveris pivotally connected in close-coupled relation to the drive projection and the pressure plate will :be positively retracted by the'leversupon-depression oftheotherends thereof.

3. In a clutch. comprising, in-rcombination,afiywheel, aback plate carried, thereby, a driven. member, an axially .movable pressure plate having aplurality of;rearwardly extending drive projections .in circumferentially spaced relation'received in registering openings providedtherefor .in .said back plate .with .a fit .close enough to transmit drive but with .suflicient clearance.to;permitrelative sliding movement, springmeans to transmit engaging pressure to said pressure :plate, and release levers pivoted ,relative to the back .plate for .causing disengagement of the .clutch, ;the :same vhaving end .portions disposed :adjacent the routertends of. the? drive projections, .the improvement which consists in the provision of means .flexibly .connectingthe driveprojections withthe adjacent ends of relation to thedrive projection and the pressureplate will be positively retracted by the levers upon. depression of the other ends thereof, the spring-tensioned pivotal ,connections frictionally resisting lateral movement ,of the drive projections relative to the levers to prevent hammering of the projections in the openings withoutthe use of any other anti-hammer means.

4. In a clutch comprising, in combinatioma (fly heel,

,a back plate carried thereby, a drivenmembenan axially movable pressure plate having a plurality of rearwardly extending drive projections in .circumferentially spaced vrelation received in registering openings provided thereforin said back plate with a fit close enough to transmit drive but with sufficient clearance to permit relative-sliding movement, spring means to transmit engaging pressure to said pressure plate, and release levers pivoted relative to the back plate for causing disengagement of the clutch,jthere being adjustable clearance takeup screws threaded in said drive projections and having headedends projecting rearwardly therefrom and arranged to .be en- :gaged by endportions of the levers, the improvement which consists in the .provision incombination .with ,said adjustable-screws of means pivotallyand swivelly connecting the headed endsof said screws with theadjacent ends of the release levers so thatthescrewsiare rotatably adjustable .wi-thout disconnection from :the :levers and the pressure plate is positively retracted by the levers upon depressionof the other ends of said levers, the pivotal connectingmeans. including friction :drag meansvarranged to exert appreciable. frictional resistance to, lateral move- ,ment of the screw heads relative to theleversin the nor- ,for in said rback;plate, spring meanstot-ransmit engaging pressure tosaid pressure plate,.- and release leverspivoted relative to the back plate for causingdisengagementof the. clutch,rthere being adjustable clearance takeup screws threaded-in vsaid drive projections and having headed .ends projecting.rearwardly'therefrom and arranged totbc engagedrby endportionsof the levers, the improvement whichconsists in the provision.in:combin-ation with said .adjustable'screws ,of :means flexi-bly interconnecting .the ,headedends of .said screws with the adjoining ends ,of

said release-levers toiretract-rthe pressure plate when-the release levers :are moved to disengage the'clutch, .said means.comprising generally U-shaped return link-members one associated with each lever and related screw -head,,having the. cross-portion oftheU "straddling a porvtion of the end-ofthe.levenpermitting pivotal-movement of thelatter and having the arms of the U extending toward-thelscrew:headand attached to the opposite-ends ,of an elongated plate that is rigidly supported .intermediate its ends under the screw head -in transverse relation to the screw, so that the leveris pivotally aand swivelly connected in'close-coupled relation'to the screw head and the pressure plate willbepositively retracted by the levers upondepression of-the otherends thereof.

6. In a clutch comprising, in combination, a flywheel,

.aback-plate-carriedthereby,a driven member, anaxially movablepressure plate having a plurality of rearwardly extending drive projections in circumferentially spaced relation received in registering openings provided-therefor-in said backplate with a fit close enough-to transmit .drive but with sufiicientclearance to permit relativeslid- 'ing, movement, springs ,meanstotransmit engaging pressure screws of means flexibly interconnecting the headed'ends of said screws .with the adjoining ends ofsaidrelease levers to retract the pressure plate when the release, levers arenioved-to disengage the clutch, said means comprising generally :U-shaped return link members, one associated with each lever andrelated screw head, having the crossportion of the U straddling a portion of the endof the lever permitting pivotal movement of the latter and having the arms of the U extending toward the screw head and attached to the opposite ends of an elongated spring plate that is rigidly supported intermediate its-ends under the screw head in transverse relation tothe screw, the end portions of the plate being sprung toward the leverin the connection of the arms ofthe link-therewithysothatthe lever is pivotally connected in spring-tensioned, closecoupled relation to the screw head and-the pressure-plate will be positively retracted by the'levers upon depression of the other ends thereof, the spring-tensioned pivotal connections frictionally resisting lateral movement'of the screwheads relative to the levers to prevent hammering of the projections in the op enings=without:the use vof.any other anti-hammer means.

7. In a clutch comprising, in combination, azfiywheel,

i a back plate carried thereby, a driven member, an axially movable pressure plate having a plurality of rearwardly extending drive projections in circumferentially spaced relation received in registering openings provided therefor in said back plate with a fit close enough to transmit having the cross-portion of the U straddling a portion of the end of the lever permitting pivotal movement of the latter and having the arms of the U extending toward the projection and attached to the opopsite ends of an elongated plate that is rigidly supported intermediate its ends on the drive projection in transverse relation thereto, the cross-portion of the U being resilient and bowed toward the lever and being subjected to deflection in the direction of straightening in the connection of the arms of the link with the plate, so that the lever is pivotally connected in spring-tensioned, close-coupled relation to the drive projection and the pressure plate will be positively retracted by the levers upon depression of the other ends thereof, the spring-tensioned pivotal connections frictionally resisting lateral movement of the drive projections relative to the levers to prevent hammering of the projections in the openings without the use of any other anti-hammer means.

8. In a clutch comprising, in combination, a flywheel, a back plate carried thereby, a driven member, an axially movable pressure plate having a plurality of rearwardly extending drive projections in circumferentially spaced relation received in registering openings provided therefor in said back plate with a fit close enough to transmit drive but with sulficient clearance to permit relative sliding movement, spring means to transmit engaging pressure to said pressure plate, and release levers pivoted relative to the back plate for causing disengagement of the clutch, the same having end portions disposed adjacent the outer ends of the drive projections, the improvement which consists in the provision of means flexibly connecting the drive projections with the adjacent ends of the release levers, comprising generally U-shaped return link members, one associated with each lever and related drive projection, having the cross-portion of the U straddling a portion of the end of the lever permitting pivotal movement of the latter and having the arms of the U extending toward the projection and attached to the opposite ends of an elongated spring plate that is rigidly supported intermediate its ends on the drive projection in transverse relation thereto, the cross-portion of the U being resilient and bowed toward the lever and being subjected to deflection in the direction of straightening in the connection of the arms of the link with the plate, and the end portions of the plate being also sprung toward the lever in the connection of the arms of the link with the plate, so that the lever is pivotally connected in spring-tensioned, close-coupled relation to the drive projection and the pressure plate will be positively retracted by the levers upon depression of the other ends thereof, the spring-tensioned pivotal connections frictionally resisting lateral movement of the drive projections relative to the levers to prevent hammering of the projections in the openings without the use of any other anti-hammer means.

9. In a clutch comprising, in combination, a flywheel, a back plate carried thereby, a driven member, an axially movable pressure plate having a plurality of rearwardly extending drive projections in circumferentially spaced relation received in registering openings provided therefor in said back plate with a fit close enough to transmit drive but with suflicient clearance to permit relative sliding movement, spring means to transmit engaging pressure to said pressure plate, and release levers pivotedrelative to the back plate for causing disengagement of the clutch, there being adjustable clearance takeup screws threaded in said drive projections and having headed ends projecting rearwardly therefrom and arranged to be engaged by end portions of the levers, the improvement which consists in the provision in combination with said adjustable screws of means flexibly interconnecting the headed ends of said screws with the adjoining ends of said release levers to retract the pressure plate when the release levers are moved to disengage the clutch, said means comprising generally U- shaped return link members, one associated with each lever and related screw head, having the cross-portion of the U straddling a portion of the end of the lever permitting pivotal movement of the latter and having the arms of the U extending toward the screw head and attached to the opposite ends of an elongated spring plate that is rigidly supported intermediate its ends under the screw head in transverse relation to the screw, the crossportion of the U being resilient and bowed toward the lever and being subjected to deflection in the direction of straightening in the connection of the arms of the link with the plate, so that the lever is pivotally connected in spring-tensioned, close-coupled relation to the screw head and the pressure plate will be positively retracted by the levers upon depression of the other ends thereof, the spring-tensioned pivotal connections frictionally resisting lateral movement of the screw heads relative to the levers to prevent hammering of the projections in the openings without the use of any other anti-hammer means.

10. In a clutch comprising, in combination, a flywheel, a back plate carried thereby, a driven member, an axially movable pressure plate having a plurality of rearwardly extending drive projections in circumferentially spaced relation received in registering openings provided therefor in said back plate with a fit close enough to transmit drive but with suificient clearance to permit relative sliding movement, spring means to transmit engaging pressure to said pressure plate, and release levers pivoted relative to the back plate for causing disengagement of the clutch, there being adjustable clearance takeup screws threaded in said drive projections and having headed ends projecting rearwardly therefrom and arranged to be engaged by end portions of the levers, the improvement which consists in the provision in combination with said adjustable screws of means flexibly interconnecting the headed ends of said screws with the adjoining ends of said release levers to retract the pressure plate when the release levers are moved to disengage the clutch, said means comprising generally U-shaped return link members, one associated with each lever and related screw head, having the cross-portion of the U straddling a portion of the end of the lever permitting pivotal movement of the latter and having the arms of the U extending toward the screw head and attached to the opposite ends of an elongated spring plate that is rigidly supported intermediate its ends under the screw head in transverse relation to the screw, and the end portions of the plate being also sprung toward the lever in the connection of the arms of the link with the plate, so that the lever is pivotally connected in spring-tensioned, close-coupled relation to the screw head and the pressure plate will be positively retracted by the levers upon depression of the other ends thereof, the springtensioned pivotal connections frictionally resisting lateral movement of the screw heads relative to the levers to prevent hammering of the projections in the openings without the use of any other anti-hammer means.

11. In a clutch comprising, in combination, a flywheel, a back plate carried thereby, a driven member, an axially :for in ssai dlbackplatevwitha. fit. close enough. to-itransmit .drive but with -sutficient clearance ;to permit relative! sliding movement, spring .means to transmit engaging pressure ,to -.said pressure plate, and .release levers pivoted relative .to the back .plate forgcausing disengagementi-ofithe clutch,. the. same. having endrportions disposed adjacenhthe onterendsof .thedrive projections, the improvement whichtconsistsin theiprovision of meansflex- .ib1y.con-necting the.drive projectionswith the adjacent ,ends, of theirelease levers, comprisinglgenerally U-shaped .return link members, one,associated=twith each-lever. and related driveprojection havingthe cross-portion of the U straddling a portion of the end of the lever permitting pivotal movement of the latter and having the arms of the U extending toward the projection and attached to the opposite ends of an elongated plate that is rigidly supported intermediate its ends on the drive projection in transverse relation thereto, the cross-portion of the U being resilient and bowed toward the lever and being subjected to deflection in the direction of straightening in the connection of the arms of the link with the plate, so that the lever is pivotally connected in spring-tensioned, close-coupled relation to the drive projection and the pressure plate will be positively retracted by the levers upon depression of the other ends thereof, the springtensioned pivotal connections frictionally resisting lateral movement of the drive projections relative to the levers to prevent hammering of the projections in the openings without the use of any other anti-hammer means, the arms of the U being resilient and having shoulders projecting inwardly from their free end portions which are adapted to be engaged with snap action behind the end portions of the plate when the arms are spread apart in moving the shouldered end portions into coupling position.

12. In a clutch comprising, in combination, a flywheel,

a back plate carried thereby, a driven member, an axially movable pressure plate having a plurality of rearwardly extending drive projections in circumferentially spaced relation received in registering openings provided therefor in said back plate with a fit close enough to transmit drive but with suflicient clearance to permit relative sliding movement, spring means to transmit engaging pressure to said pressure plate, and release levers pivoted relative to the back plate for causing disengagement of the clutch, the same having end portions disposed adjacent the outer ends of the drive projections, the improvement which consists in the provision of means flexibly connecting the driveprojections with the adjacent ends of the release levers, comprising generally U-shaped return link members, one associated with each lever and related drive projection, having the cross-portion of the U straddling a portion of the end of the lever permitting pivotal movement of the latter and having the arms of the 'U extending toward the projection and-attached to the opposite ends of an elongated spring plate that is rigidly supported intermediate its ends on the drive projection in transverse relation thereto, the cross-portion of the U being resilient and bowed toward the lever and being subjected to deflection in the direction of straightening in the connection of the arms of the link with the plate, and the end portions of the plate being also sprung toward the lever in the connection of the arms of the link with the plate, so that the lever is pivotally connected in spring-tensioned, close-coupled relation to the drive projection and the pressure plate will be positively retracted by the levers upon depression of the other ends thereof, the spring-tensioned pivotal connections frictionally resisting lateral movement of the drive projections relative to the levers to prevent hammering of the projections in the openings without the use of any other anti-hammer means, the arms of the U being resilient and having shoulders projecting inwardly from their free end per ,tions which. are adapted to be engaged with snap ;;action behind theend ,portionsiof theplate when the arms :Bl'6

spread apart in moving ;the shouldered 'endjportionsinto coupling position.

13. Ina clutch comprising, in combination, azflywheel, .a: back plate carried'thereby, adriven, member, an; axially movable pressure plate :having a plurality of rearwardly extending drive projections in circumferentially spaced relation received in registering openings providedtherefor in said back plate with ,a fit closeenoughto transmit drivebut withsufiicientclearance to permitrelative sliding .movement, ,springmeans to transmit engaging I pressure tosai-d pressureplate, vandrelease leverspivoted relative to the :back plate for causingdi-sengagementtof the clutch, there beingadjustable clearance takeup; screws threaded in said drive projections landihavingzheadedtends projecting rearwardly therefrom and arranged to be engaged by end portions of the levers, the improvement which consists in the provision in combination with said adjustable screws of means flexibly interconnecting the headed ends of said screws with the adjoining ends of said release levers to retract the pressure plate when the release levers are moved to disengage the clutch, said means comprising generally U-shaped return link members, one associated with each lever and related screw head, having the cross-portion of the U straddling a portion of the end of the lever permitting pivotal movement of the latter and having the arms of the U extending to- Ward the screw head and attached to the opposite ends of an elongated spring plate that is rigidly supported intermediate its ends under the screw head in transverse relation to the screw, the cross-portion of the U being resilient and bowed toward the lever and being subjected to deflection in the direction of straightening in the connection of the arms of the link with the plate, so that the lever is pivotally connected in spring-tensioned, closecoupled relation to the screw head and the pressure plate will be positively retracted by the levers upon depression of the other ends thereof, the spring-tensioned pivotal connections frictionally resisting lateral movement of the screw heads relative to the levers to prevent hammering of the projections in the openings without the use of any other anti-hammer means, the arms of the U being resilient and having shoulders projecting inwardly from their free end portions which are adapted to be engaged with snap action behind the end portions of the plate when the arms are spread apart in moving the shouldered end portions into coupling position.

14. In a clutch comprising, in combination, a flywheel, a back plate carried thereby, a driven member, an axially movable pressure plate having a plurality of rearwardly extending d-rive projections in circumferentially spaced relation received in registering openings provided therefor in said back plate with a fit close enough to transmit drive but with sufficient clearance to permit relative sliding movement, spring means to transmit engaging pressure to said pressure plate, and release levers pivoted relative to the back plate for causing disengagement of the clutch, there being adjustable clearance takeup screws threaded in said drive projections and having headed ends projecting rearwardly therefrom and arranged to be engaged by end portions of the levers, the improvement which consists in the provision in combination with said adjustable screws of means flexibly interconnecting the headed ends of said screws with the adjoining ends of said release levers to retract the pressure plate when the releae levers are moved to disengage the clutch, said means comprising generally U-shaped return link members, one associated with each lever and related screw head, having the cross-portion of the U straddling a portion of the end of the lever permitting pivotal movement of the latter and having the arms of the U extending toward the screw head and attached to the opposite ends of an elongated spring plate that is rigidly supported intermediate its ends under the screw head in transverse relation to the screw, and the end portions of the plate being also sprung toward the lever in the connection of the arms of the link with the plate, so that the lever is pivotally connected in spring-tensioned, close-coupled relation to the screw head and the pressure plate will be positively retracted by the levers upon depression of the other ends thereof, the spring-tensioned pivotal connections frictionally resisting lateral movement of the screw heads relative to the levers to prevent hammering of the projections in the openings without the use of any other anti-hammer means, the arms of the U being resilient and having shoulders projecting inwardly from their free end portions which are adapted to he engaged with snap action 'behind the end portions of the plate when the arms are spread apart in moving the shouldered end portions into coupling position.

References Cited in the file of this patent UNITED STATES PATENTS Wales July 22, 1902 Wemp Dec. 7, 1926 Doty Dec. 28, 1937 Hunt May 21, 1940 Thelander Sept. 17, 1940 Wiley Oct. 1, 1940 Tinnerman Dec. 9, 1941 Woodward Sept. 8, 1942 Tinnerman et a1 July 20, 1943 Thelander July 13, 1948 Banker June 9, 1953 Carbary Oct. 27, 1953 

